The objective of this research project is to determine the role of viruses and interferon in immunologic and immunopathologic processes. The observation that immune interferon could be produced by peripheral blood leukocytes in vitro on an immune specific basis suggested that it might be produced in vivo in various autoimmune disorders. We found immune interferon in the sera of patients with active immunologic diseases, such as systemic lupus erythematosus, rheumatoid arthritis, scleroderma and Sjorgren's syndrome. Furthermore, the presence of interferon was correlated with clinical disease activity. It is possible that the production of interferon may contribute to immunologic aberrations in autoimmune diseases and also protect the already compromised host from viral infections.